Means for detecting metal particles in nonmetallic material



' 1,640,524 Aug' 30 1927' R. w. AUGUSTINE MEANS FOR DETECTING METAL PARTICLES IN NONMETALLIC MATERIALS Filed Feb. 24. 1921 50 www y 33 f all@ Patented Aug. 3o, 1927.

UNITED STATES -PATENT OFFICE.

, ROYy WIIJBEBT AUGUSTINE, OE OAK PAK, ILLINOIS, ASSIGNOR TO WESTERN ELEC- TRIC COMPANY, INCORPORATED, OF JNEWYOBK, N. Y., A CORPORATION OE NEW Yonx.

MEANS ron DETEGTING METAL PAETIcEEs 1N NoNMErALIJIc MATERIAL.

c App'neeun mea February 24, 1921. serial No. 447,606.

This invention -relatesto a means for detecting metal particles` innon-metallic material, and more particularlyl tofthe. detecttion of metal particles-in rubber scrap.

In the use of rubber dust for the molding 'of partsv which are laterpr led with diamondtools the presence of etal parnticles isvery objectionable, in that such metal particles are very injuriousjto diamond profiling tools used in the finishing of these parts. Such metal .particles are 4also injurious to grinding rolls, andit therefore becomes important to remove. all metal particles from the rubber scrapv before it has reached the grinding rolls. A large percentage of the particles found in rubber scrap are non-magnetic, and it is therefore' not .possible to remove these particles by electrical methods. If, however, somey means is provided fordetecting all metal particles, they may be removed by hand before the scilzpkrubber. is turned intothe grinding `ro s.

' The object of this invention is to provide a sensitive means for detecting the minute becomeunbalanced and this in turn w11l be metal particles in scrap rubbers,

of this invention, therejis provided a sensi- 'tive induction balance circuit through the:

relay 33, thereby closmg th1s contact 32 and vcompleting the circuitfor the relay 31 which field of which a conveyor of non-metallic material carrying the scrap rubber passes. The induction balance .is connected with amplifying means for `controlling a circuit through a motor driving means whichdrives the conveyor whereby when a metal particle enters the field of the induction balance the driving motor is automatically stopped, thereby enabling the operator to remove the material containing the metal,

The invention is diagrammatically illusltrated in the accompanying` drawing formt ling a part of this specification.

In uns drawing 5 ena 6 designate, me:

airs :of coilsl 'of' a rigidly 'constructed ughes induction-balance clrcuit. The primaries 7 and 8 of these coils are connected with the terminalsA of abhi'gh frequency alternating current source 9, and the secondaries 10 and' 11 are connectedyto the input side of a .plurality of` audio frequency Vthermionic.amplifiers12,513, and 14. The amplifying .circuit also includes amphfymg transformers 15 and. 16.

Passing through the pair of coils 7' and 10 of the induction balance is a belt 20 of 'canvas or suitable non-metallic material which .is adapted to receive rubber scrap from a hopp'er 21 and deliver it into a. second hopper 22. This belt is mounted upon rollers 23 and 2 4, the roller 24 being driven from la motor 25. This motor is in clrcuitwith a suitable source of` drivin-g current, not shown, and has included in its circuit a normally closed contact 30 -of a relay 31 which is adaptedto be energized over a circuit including a normally opened contact 32 of a relay 33 which is, connect ed in the output circuit of the final ampliiier 14. i

In the practicaloperation of this mechanism for locating metal particles in nonlmetallic* material such as`\rubber scrap, the

rubber scrap will be fed upon the belt 20 from the hopper 21 carried through the coils 7 andr10 of the induction balance by the rotation of. the Vroller 24 driven by the motor 25. f Whena metal particle is brought within thje-A thermionic amplifiers 12, 13, and 14, the

amplification being suiiicient to operate the will, open its contact 30, thereby interrupting the circuit of the motor 25, and stop the -belt 20Cuntil the metal has been removed from the iield of the induction balance.

' What is claimed is: 1

-1. 'In a mechanism for detecting metal particles in non-metallic material, an induction balance, `a conveyor for the 4material ,adapted to pass through the direct magnetic field o/f the induction balance, driving mechanism' for' said conveyor, Iand means cont'i'olled by the unbalance of the induction field dueto the presence of metal therein for stopping the driving mechanism. 2. In a mechanism for detecting metal particles in non-metallic material, an induction balance, a'conveyor for the material passing through the direct )magnetic field ofv said balance,. drivin mechanism lforI said ,conveyor, af circuit oi' the driving mechanism, a circuit breaker for controlling the circuit of .the-'driving mechanism, an amplifying apthe induction balance, driving mechamsm for said conveyor, and thermionic amplifiers unbalance ofthe induction balance for stopping the driving mechanism. 4.' In a mechanism for detecting metal particles in non-metallic material, an-induc responsive to tion balance including a pair of coils having,

a hollow core, a conveyor for ther material adapted to pass through the hollow cores of said coils, and subject metallic particles carried thereby to the direct magnetic field of said coils, driving 4mechanism for the said conveyor, and means controlled by the unbalance Aof the induction field due to the presence of metal therein for stopping the diiving mechanism.

' tion, balance,

l5. In a mechanism particles in non-metallic material, an induction balance including a pair-of coils having a hollow core, a non-metallic conveyor for the material adapted tol pass through the hollow cores of said coils, and subject metallic particles carried thereby to the direct magnetic fields of said coils, driving mechanism for the said non-metallic conveyor, and means controlled.' by the unbalance of the induction ield due to the presence of metal therein for stopping the driving mechanism. 6. In a mechanism for detecting metal particles in non-metallic material, an 'induca conveyor for the material for detecting metal passing 'through the direct magnetic field of the induction l balance, driving mechanism for said conveyor, a circuit for thedriving mechanism, a circuit breaker for controlling the circuit of the driving' mechanism, and thermionic amplifiers responsivev to the unba-lance of the induction balance for causing the operation of said circuit breaker.

7. -In a mechanism for detecting metal particles in non-metallic material, an induction balance including a pair of coils having hollow cores, a non-metallic conveyor for the material adapted to pass through the hollow cores of said colls, and subject metallic parti? cles carried thereby to the direct magnetic field of said coils, driving mechanism for said conveyor, 'a circuit for the driving mechanisrn, a circuit breaker for controlling- Vthe circuit of the driving mechanism, and thermionic lamplifiers responsive to the-unbalance of the induction balance for causing the operation of said circuit breaker.

8. In a mechanism :for detecting meta particles in non-metallic material,` anl'inductive balance comprising two pairs of coils, the coils of each pair being electrically balanced against each other, a conveyor forv the material encircled by one pair of said coils', said material being therebysubjectedto the magnetic eld produced by said coils, d riving mechanism for said conveyor,\and means controlled by an unbalance of said coils due to the presence of metal therein for stoppinglthe driving mechanism. V A

In' witness whereof, I hereunto subscribe .my name this 3rd day ofv February, A. D.,

ROY WILBERT' AUGUSTINE. 

